1. Field of the Invention
The present invention relates generally to devices and methods for severing soft tissue. In particular, the present invention relates to devices and methods that enhance the accuracy of lesion excision, through severing, capturing and removal of a lesion within soft tissue. Furthermore, the present invention relates to devices and methods for the excision of breast tissue based on the internal anatomy of the breast gland.
2. Description of Related Art
Surgery plays an important role in the diagnosis and treatment of cancer. In the case of breast cancer, surgery comprises a critical component of medical care where early diagnosis and treatment have demonstrated a significant improvement in survival.
Currently the surgical treatment of a breast cancer does not consider anatomical boundaries within the breast tissue. Anatomical boundaries are, however, important in considering the mechanism of cancer spread within the breast. The breast consists of 15 to 20 lobes that begin centrally beneath the nipple-areolar complex and extend in a radial pattern to the periphery of the gland. Milk is produced in numerous small lobules that connect to one or more main ducts within the lobe. Breast cancer begins in the epithelial cells that line the smaller branching ducts entering the lobules. The cancerous cells may multiply and spread within the ducts of the involved lobe and/or may multiply and form a defined mass. Cancerous spread within the ducts is not appreciated by mammography unless microcalcifications are present. Extension within the ducts may also be missed on pathological examination of the specimen unless a sample is taken exactly at the level of the involved duct. Using current methods of lumpectomy and examination of the specimen, these limitations may lead to inadequate surgical treatment of the cancer.
An ultrasound examination of the internal breast anatomy as described in U.S. Pat. No. 5,709,206 to Teboul, can be utilized to study the lesion and its relation to the lobe in which it is developed. By using axial ductal ultrasound scanning, identification of the affected lobe, lesion size, position within the lobe, and the possibility of other lesions within the affected lobe (e.g. multifocal cancer), and/or spread within the ducts can be delineated prior to surgical treatment.
A number of patents and publications describe excisional devices designed to remove lesions particularly from within the breast. For example, U.S. Pat. No. 6,022,362 to Lee et al. describes an excisional biopsy device for breast tissue, the device employing a tubular member having a window. A portion of the cutting tool is configured to selectively bow out of and to retract within the window. In operation, the biopsy device is inserted into soft tissue and rotated while the cutting tool is selectively bowed away from the tubular member thus severing tissue for biopsy. A tissue collection bag that is externally affixed to the tubular member may be employed to collect the severed tissue. The window is of fixed length thereby limiting the size of the excised specimen. This limits the size of lesions that can be effectively excised as a single specimen and, in addition, an entire lobe of the breast cannot be excised using this device.
U.S. Pat. No. 6,267,759 to Quick describes a cutting loop attached to a rotatable shaft. The cutting loop energized by radio frequency energy may be fashioned to form different shapes, however, there is no mechanism to adjust the size of the cutting loop. This limits the size of lesions that can be effectively excised as a single specimen and does not allow this device to excise an entire lobe.
U.S. Pat. No. 6,331,166 B1 to Burbank et al. describes a tissue acquisition system that includes radio frequency cutter loops which are extendible out of a cannula to cut cylindrical tissue samples. The cutter loops are also of fixed diameter thereby limiting the size of the lesion that can be excised as a single specimen and does not allow the device to excise an entire lobe.
Accordingly, there is a need for a surgical excisional device that can accurately excise a lesion as a single tissue specimen, that can adapt to lesions of different sizes by varying the size of the cutting mechanism, and that can capture and remove the specimen through a small incision. The device should minimize scarring to the remaining breast tissue by including within the specimen only the necessary amount of surrounding normal breast tissue required to obtain adequate margins. The method of severing and retrieving the sample of tissue should be performed in a manner that minimizes the risk of cancer cell dissemination. Further, there is a need for a therapeutic surgical device and/or method of treatment of breast cancer, that accurately excises part of a lobe, an entire lobe or more than an entire lobe as a single specimen.
The present invention relates to devices and methods that enhance the accuracy of lesion excision, through severing, capturing and removal of a lesion within soft tissue. Furthermore, the present invention relates to devices and methods for the excision of breast tissue based on the internal anatomy of the breast gland. It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device, or a method. Several inventive embodiments of the present invention are described below.
The devices and methods described herein are preferably adapted to accurately and safely excise a mass of tissue from the breast or other soft tissue as a single specimen and with minimal invasiveness. The amount of tissue excised is variable and preferably not limited by the mechanism of the device. Further, the devices and methods improve the accuracy of positioning the device with respect to the lesion.
The devices and methods facilitate safe capture and removal of the severed tissue from the body to minimize potential cancer cell dissemination. Moreover, the devices and methods are adapted to accurately and safely excise part of a lobe of a breast, the entire lobe or more than the entire lobe for therapeutic surgical treatment of breast cancer. Optionally, the devices and methods provide for marking or labeling the specimen in vivo to enable specimen orientation once removed from the body.
According to a preferred embodiment, a tissue severing device generally comprises a guide, a cutting tool contained within the guide and capable of forming a cutting loop extending from the guide and having a loop extension axis defined by the direction in which the cutting loop extends, and an extension means for controlling the degree to which the cutting loop extends from the guide. The guide comprises two co-linear, co-extensive guide lumens longitudinally extending from a proximal region to a distal terminus along a guide axis and the guide lumens have co-extensive distal segments terminating in distal tips from which the cutting loop extends. The angle of each distal segment in relation to the guide axis is generally fixed.
The distal tips may be at a generally fixed distance therebetween such that the width of the cutting loop when the cutting loop is extended is generally fixed. Alternatively, the device may further comprise a width adjuster for selectively moving the distal tips of the distal segments relative to each other to thereby selectively adjust the width of the cutting loop. The width adjuster varies the distance between the distal tips by rotating at least one of the guide lumens.
According to another preferred embodiment, a tissue severing device generally comprises a guide, a cutting tool contained within the guide and capable of forming a cutting loop having a loop extension axis defined by the direction in which the cutting loop extends, an extension means for controlling the degree to which the cutting loop extends from the guide, and a distal segment positioning means for varying the direction of each distal segment with respect to the guide axis to thereby adjust the angle between the loop extension axis and the guide axis and selectively position the cutting loop with respect to the guide axis. The guide comprises two co-linear, co-extensive guide lumens longitudinally extending from a proximal region to a distal terminus along a guide axis and the guide lumens have co-extensive distal segments terminating in distal tips from which the cutting loop extends and deformable regions immediately proximal to the distal segments. The deformable regions facilitate in changing the direction of the distal segments with respect to the guide axis.
The distal segment positioning means may comprise retraction cables, each attached to one of the distal segments such that selective tightening and relaxing of the retraction cables adjusts the direction of the distal segments with respect to the guide axis. In addition, selective tightening and relaxing of the retraction cables may further position the cutting loop when extended so as to adjust the angle between the loop extension axis and the guide axis to thereby reposition the cutting loop with respect to the guide axis. The retraction cables may be at least partially and movably disposed within said guide lumens. In an alternative, the deformable regions may comprise a shape-memory material.
The distal tips may be at a generally fixed distance therebetween such that the width of the cutting loop when the cutting loop is extended is generally fixed. Alternatively, the device may further comprise a width adjuster to facilitate in selectively moving the distal tips of the distal segments relative to each other to thereby selectively adjust the width of the cutting loop. The width adjuster moves the distal tips of the distal segments and varies the distance between the distal tips by rotating at least one of the guide lumens.
According to yet another preferred embodiment, a tissue severing device generally comprises a guide comprising a guide lumen, a cutting tool having a fixed end and is at least partially contained within the guide lumen when in a stored configuration and extendible from a distal tip thereof, an extension means for controlling the degree to which the cutting loop extends from the guide lumen, and a width adjuster for selectively adjusting the width of the cutting loop. The guide lumen longitudinally extends from a proximal region to a distal terminus along a guide axis and has a distal segment terminating in the distal tip. Extension of the cutting tool from the guide lumen forms a cutting loop having a loop extension axis defined by the direction in which the cutting loop extends.
According to a preferred embodiment, a method for excising a lobe from within a human patient""s breast generally comprises locating the lobe to be excised within the breast and excising at least a part of the lobe utilizing a tissue severing device. The method may further comprise locating a lesion within a lobe of the breast, evaluating the size of the lesion, identifying any extensions of the lesion and any additional lesions within the lobe, and determining from the locating, evaluating, and identifying whether to excise at least a part of the lobe, the entire lobe or the entire lobe plus additional surrounding tissue in the excising in order to remove the lesion or lesions from the breast.
The identifying step may generally comprise identifying any extensions of the lesion within the duct system and evaluating the lobe of the breast for additional lesions. Moreover, at least one of the locating, evaluating, identifying, and employing may be carried out using a radiological imaging modality such as ultrasound imaging or magnetic resonance imaging (MRI).
According to another preferred embodiment, a method for removing a lesion from a patient generally comprises locating the lesion to be severed and removed from within a selected region of the patient, inserting a guide through an incision, advancing the guide into the selected region, extending a cutting tool contained within the guide from the distal tips of the two guide lumens to form a cutting loop having a loop extension axis defined by the direction in which the cutting loop extends, and moving the cutting loop using the guide along the guide axis to sever tissue containing the lesion from the selected region.
The guide advanced by the method generally comprises two co-linear, co-extensive guide lumens longitudinally extending from a proximal region to a distal terminus along a guide axis and having co-extensive distal segments terminating in distal tips. In one embodiment, the angle of each distal segment relative to the guide axis is generally fixed.
Alternatively, the guide lumens of the guide advanced by the method have deformable regions immediately proximal to the distal segments that facilitate in changing the direction of each distal segment with respect to the guide axis. The method may further comprise varying the direction of at least one of the distal segments with respect to the guide axis, thereby changing the angle between the loop extension axis and the guide axis, whereby the cutting loop is repositioned with respect to the guide axis. The distal segments of the guide lumens may optionally maintain a generally fixed distance therebetween. Alternatively, the method may further comprise, prior to or during the extending, varying the distance between the distal segments to selectively widen or narrow the cutting loop.
According to yet another preferred embodiment, the guide advanced by the method comprises a guide lumen longitudinally extending from a proximal region to a distal terminus along a guide axis, the guide lumen has a distal segment terminating in a distal tip and the cutting tool has a fixed end at least partially contained within the guide lumen when in a stored configuration and is extendable from the distal tip thereof to form a cutting loop.